We describe a new symmetric product ciphering
algorithm that operates iteratively on an arbitrary square block of plaintext with the
only constraint that the blocklength has to be an integral power of 2. Permutations are
induced by the highly unstable nonlinear dynamics of chaotic Kolmogorov flows, while
substitutions are implemented using add-with-carry or subtract-with-borrow generators.
Encryption performance is excellent in hard- and software which is based on the fact that
only additions, subtractions and bit-shifts, but no time-consuming operations like
multiplication or exponentiation are necessary for implementing the cipher.